The invention relates to a padlock with a removable cylinder lock mechanism. There are previously known padlocks in which the elements of the lock mechanism can be replaced, thus making it possible to change the opening combination of the lock. Examples of this are shown in U.S. patent application No. 535,549, filed Sept. 26, 1983 which is a continuation of U.S. Pat. application No. 240,193, filed 1981-03-03, now abandoned and in U.S. patent specification No. 3,835,675. In these known padlocks, there is a slideable lid element, which has to be removed before the replacement of the lock mechanism is possible.